Mortgage Servicing Rights and Related Liabilities - Servicing Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Transfers and Servicing [Abstract]
Contractually specified servicing fees(1)	$ 327	$ 276
Other service-related income(1)	48	145
Incentive and modification income(1)	9	14
Late fees(1)	19	18
Mark-to-market adjustments(2)	553	365
Amortization, net of accretion(3)	(202)	(167)
Other(4)	(38)	(83)
Total revenues - Servicing	716	568
Cumulative incurred losses related to advances and other receivables associated with inactive and liquidated loans	6	12
Servicing fee income accretion expense	$ 33	$ 76